ASML, the world's third-largest semiconductor equipment maker, said last week it had counter-sued rival Nikon, after the Japanese company launched a wide-ranging patent battle against the Dutch company.

ASML's lawsuits involve semiconductor-manufacturing equipment, flat panel display manufacturing equipment and digital cameras. They were brought in Japan by ASML on its own and jointly with its partner, Carl Zeiss, a German maker of optical systems and medical devices.

ASML dominates the market for lithography machines used by the world's biggest chipmakers to make circuits ever smaller, faster and more powerful. It generates about 80 per cent of revenues in that market, ahead of Nikon and Canon Inc, according to ratings agency Fitch.

The round of lawsuits and countersuits follows efforts to renegotiate a patent deal between ASML and Nikon that expired in 2014 and threatens to revive legal battles that stretch back to the turn of the century.

Patent wars are infrequent in the technology industry, which depends on thousands of patents that companies frequently cross-license to rivals, while reserving their most strategic intellectual property to create proprietary products.

Intense competition sometimes spills over into costly court cases, as seen in a string of patent wars among smartphone makers in recent years.

ASML, Nikon and Zeiss settled litigation in 2004 after the International Trade Commission found the Dutch company had not infringed Nikon patents.

Nikon, the world's eighth-largest chip equipment maker, said on Monday it had filed a patent case against ASML and Zeiss, accusing them of using its lithography technology without permission. The Tokyo-based company filed a string of suits in the Netherlands, Germany and Japan.

"Now that Nikon has decided to take this dispute to court, we also have to enforce our patent portfolio, and we will do this as broadly as possible," ASML chief executive Peter Wennink said, adding it had tried for years to reach a cross-licensing agreement with Nikon.